System.Runtime.CompilerServices.ExtensionMarkerAttribute
This attribute is used to mark extension members and associate them with a specific marker type (which provides detailed information about an extension block and its receiver parameter).
This attribute should not be used by developers in source code.
namespace System.Runtime.CompilerServices
{
internal sealed class ExtensionMarkerAttribute : Attribute
{
public string Name { get; }
public ExtensionMarkerAttribute(string name);
}
}